This invention relates to a sail for sailing-boats.
It has been found that the uppermost portion of the sail, the top of the sail, of the normal sails used today on sailing-boats does not contribute to creating the negative pressure required for creating the motive force. If it should be possible, in some way, to have the uppermost portion of the sail contribute to a greater negative pressure formed, the motive force should increase and consequently also the speed of the boat.